Steel Suppliers and stockholders - KV Steel Services, Darlaston, West Midlands

EN8 Steel

BS970: 1955 EN8, BS970/PD970: 1970 onwards 080M40.
Related European grades: C40, C45, Ck40,Ck45, Cm40, Cm45,
Werkstoff no. 1.0511, 1.1186, 1.1189.
US Grades: SAE (AISI) 1039, 1040, 1042, 1043, 1045.

EN8 flats and squares in stock now >>

EN8 is usually supplied untreated but can be supplied to order in the normalized or finally heat treated (quenched and tempered to "Q" or "R" properties for limiting ruling sections up to 63mm), which is adequate for a wide range of applications.  Please refer to our selection guide for comparisons.

EN8 is a very popular grade of through-hardening medium carbon steel, which is readily machinable in any condition. (Refer to our machinability guide). EN8 is suitable for the manufacture of parts such as general-purpose axles and shafts, gears, bolts and studs.  It can be further surface-hardened typically to 50-55 HRC by induction processes, producing components with enhanced wear resistance.  For such applications the use of EN8D (080A42) is advisable.  It is also available in a free-machining version, EN8M (212A42)

EN8 in its heat treated forms possesses good homogenous metallurgical structures, giving consistent machining properties.

Good heat treatment results on sections larger than 63mm may still be achievable, but it should be noted that a fall-off in mechanical properties would be apparent approaching the centre of the bar.

It is therefore recommended that larger sizes of EN8 are supplied in the untreated condition, and that any heat treatment is carried out after initial stock removal.  This should achieve better mechanical properties towards the core.

080M40 (EN8) Specification
Chemical composition
Carbon 0.36-0.44%
Silicon 0.10-0.40%
Manganese 0.60-1.00%
Sulphur 0.050 Max
Phosphorus 0.050 Max
Chromium -
Molybdenum -
Nickel -


080M40 (EN8) - mechanical properties in "R" condition
Max Stress 700-850 n/mm2  
Yield Stress 465 n/mm2 Min (up to 19mm LRS)
0.2% Proof Stress 450 n/mm2 Min (up to 19mm LRS)
Elongation 16% Min (12% if cold drawn)
Impact KCV 28 Joules Min (up to 19mm LRS
Hardness 201-255 Brinell  


EN8 Equivalents
BS970: 1955 EN8
1970 onwards
European C40, C45, Ck40,Ck45, Cm40, Cm45
Werkstoff No. 1.0511, 1.1186, 1.1189
US SAE (AISI) 1039, 1040, 1042, 1043, 1045


KV Steel Services is a supplier of EN8, EN8D and EN8M steel to local and national businesses. We stock EN8 in bright bar and blocks and black bar, square, flats and blocks.

EN8D Steel Bar

quality supplier of EN8 Steel